1. Field of the Invention
The present invention relates to apparatus for sterilizing foods packed in retort pouches, trays, cups, bottles, cans or the like by high-temparature and high-pressure steam.
2. DESCRIPTION OF THE PRIOR ART
Such sterilizing apparatus may include a sterilizing chamber to which a steam line and a compressed air line are connected. The sterilizing chamber also includes a drain line connected to the bottom thereof. Steam and compressed air are supplied into the sterilizing chamber through the steam line and the compressed air line, respectively. Then, a part of the mixture of steam and compressed air is exhausted from the drain line, so that the sterilizing chamber is maintained at high temperature and high pressure to sterilize packed foods stored therein.
In such conventional sterilizing apparatus, it is sometimes difficult to uniform the temperature distribution in the interior of the sterilizing chamber; there tends to be temperature differences among the upper, central and lower portions of the interior of the sterilizing chamber. The variations in the temperature difference may sometimes cause inadequate sterilization of the packed foods located in the lower and central portions of the sterilizing chamber.
Further, in such conventional sterilizing apparatus, when the temperature in the sterilizing chamber becomes lower than the predetermined temperature, steam is supplied from the steam line, irrespective of the pressure therein. In some cases, therefore, the pressure in the sterilizing chamber becomes higher than a predetermined value, which may cause undesirable deformation of the packed foods.